Method of building piers



March 1929- J. s. MILLER METHOD OF BUILDING PIERS Filed March 5, 1928 INVENTO Patented Mar. I 19, 1929.

UNITED STATES'IPATENT. OFFICE.

JAMES SMITH MILLER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE DRAVO CONTRACTING COMPANY, OF PITTSBURGH, PENNSYLVANIA,-LA CORPORATION 01' PENNSYLVANIA. v

METHOD OF BUILDING PIEBS.

Application filed March 3, 1928. Serial No. 258,824.

My invention relates to the building of the shaft where it is superposed on the founpiers, abutments, dock walls, dams, retaining walls, and such like structures, whose foundations are sunk into the earth, it may 5 be in the bed of a stream or other body of water, it may be in water-soaked or in dry ground. The invention consists in a method of building, such as to afford a better structure, more accurately located, built with better economy. I I Y The invention is illustrated in the accompanying drawings. Fig. I is a view in end elevation of a bridge pier. of familiar form and structure. Fig. II is a diagrammatic 16. view, illustrating in vertical section a method commonly followed in erecting a pier such as that shown in Fig. I. Fig. III is a plan view from above of the diagrammatic showing of Fi II. Figs. IV and V are views correspon ing to Figs. II and III and illustrating those modifications in structure and in method, in which and in the-practice of which my invention is found. Figs. VI and VII are views corresponding to Fig. IV and 2 illustrating the invention in its wider applicability.

Confining attention, first, to the building of piers, and referring to Fig. I, a bridge pier of typical form is shown. It is an integral 80v structure, which may be understood to be built of masonry, and in modern practice,-

wholly or in part of concrete. It includes a foundation or footing, l, a shaft, or, as it is often called, the neat work, 2, and this is surmounted by a coping,'3. Understanding that such piers are erected on ground which may be flushed with water, and where a foundation upon rock may be unattainable, it will be perceived that the footing 1 constitutes a wide extending enlargement upon the lower end of shaft 2, and by virtue of such greater extent affords firmer standing for the pier. The footing is commonly formed by sinking a crib or caisson to the desired or necessary depth, beneath water if need be; and into the earth, and then filling with masonry or with concrete, as the case may be, the space excavated beneath the caisson.

In the design of piers the principal dimensions are generally controlled by two factors, first, the character of the foundation bed which determines the bottom area of the foundation or footing, and, second, the superposed load which determines the base area of dation or footing.

Referring to Figs. II and III, the caisson 4 used in building a pier is, essentially, a sharp-rimmed bell, sunk edge first into the ground. -A tube or tubes5, commonly called dredging wells, enter the caisson from above,

and through the dredging wells dredging apparatus may be introduced; through them workmen have access to the interior; thro h them the excavated material is remove through them air enters to fill the excavated space. If necessary, air is introduced and maintained under pressure within the caisson,

to afford conditions under which work men may carry on excavating operations.

Through the dredging wells eventually themasonry or other material, ordinarily concrete, is introduced, to fill the space excavated beneath the caisson. And when this is done the caisson with its filling together constitute the footing of the pier. Externally the caisson will ordinarily be square cornered, as

the drawings show, for it will be perceived that the caisson constitutes the exterior por tion of the ultimately completed footing.

The caisson may be built-0f materials of one to. been followed, the offsets where the foundation ends and the shaft begins are not large and in no case known to the inventor are they of suflicient width to permit of the application of so'called dredging wells used in cais- 1 son construction outside of the shaft or neat work, nor is any case known where dredging wells have been used outside the neat lines of shaft as an aid or device for sinking a crib'or caisson nor for any other purpose. See Fig. I for illustration of commontype of pier. v

,The types of caissons now in general use are equipped with a limited number of dredging wells located within the outline of the neat work, and generally at or about the center line or'longitudinal axis of the caisson and 90 Generally, in the practice which has hitherof the shaft to be constructed thereon. There are cases where more than one line of dredging wells have been used; in all such cases, however, they have been located inside the outline of the neat work of the shaft. J

Under conditions which may arise during the lowering or sinking of caissons, due to location, or character of earth encountered, or current of stream, or all of these, it is found diflieult to maintain the longitudinal axis of the caisson in its exact location as to alignment laterally and longitudinally, and

I further in many cases it is diflicult to hold or maintain the caisson during the lowering or sinking to exact level transversely and longitudinally. It is because of the fact that some tolerance must be afiorded and allowance made for the placement of the footing, and because its actual position may but roughly approximate the ideal and desired position, that the shaft which is erected upon the footing and which rises in accurate position, is

by way of distinction termed the neat work. The object of my invention is to provide a new and uniquemethod of construction and.

of sinking or placing caissons, such as will in large measure avoid and overcome the dnficulties above enumerated,.and will reduce the tendency to tipping in landing a caisson in place. A furtherobject is to render unnecessary, in many cases, the use of detachable cofi'er-dams, so called, which are commonly .used in the present method of constructing and sinking caissons. My inventionsimplifies the work of construction and placing of caissons and foundations and thereby reduces the cost of constructing such work., The use of. my inventionwill reduce the time required for construction, an important factor where high wateror floods may beencoun tered. Incident all to the practice of my invention, the bearing load of the finished structure on un erlying soil or foundation is decreased without materially increasing the cost of construction.

M invention is found in an enlargement of tlie caisson, in employing (in the case of the'erection of a pier) a caisson for a shaft of given dimensions which shall be greater in lateral extent than. otherwise would be required, and in the arrangement of the dredging well-or dredging wells, for ordinarily there will be a plurality of these wells, symmetrically. arranged 'outside of the space which eventually-the shaftwill occupy. In

Fig. IV such a widened caisson, widened to effect the ends and purposes I have in mind,

. is indicated at 6. This widening and enlarging of the caisson will be more fully apparenton comparing Figs. III and V, and in Fig. V the outline of the caisson of Fig. III

is superposed in dotted lines, merely to indicate more fully and precisely the change and the effect of the change in dimensions. In

consequence of such lateral extension of the caisson, the dredging well or wells 7, instead of being situated within the space in which eventually the shaft 2 rises, are situated externally of that space. And these dredging wells are, as will be perceived, advantageously arranged in symmetrical grouping with respect to the longitudinal and transverse vertical axial planes of the structure.

- Because of the enlargement of the caisson in its lateral extent, its weight is more widely distributed, the pressure per unit of area is less, the pressures at symmetrically opposite points may be more fully equalized, the caisson may be sunk with better accuracy and with less tipping, and may be brought to its ultimate position with greater accuracy. In consequence of improvement in accuracyof placement, it is no longer necessary to delay the erection of the shaft until after the footing has been completed, but (in the case of the building of a pierin a river bed, for instance) the shaft may rise as the caisson sinks,

and the building of the shaft may always be carried on above thesurface of the water. In the usual practice, it being practically necessary to delay the erection of the shaft untilthe caisson has come to its ultimate position and until the footing has been completed, it is requisite (When-making erection in water) to build a coffer-dam, rising from the caisson to a height greater than the ultimate depth to which the caisson is sunk. The position of such a coifer-dam is in Fig. II'indicated at 8. Withinthis cofler-dam, afterthe footinghas been completed, the shaft 2 ultimately is built.'. Since I may proceed With shaft building while the caisson still is in cours e of descent, and so may do the shaft building always above water level, it is manifest that nocoffer-dam such as that described,

is needed. In building a pier in the old manner, if by chance circumstances justify the progressive erection of the shaft as the caisson descends it still is necessary to leave'a dredging well open through the shaft, to be filled eventually, after the caisson has reached its position and the excavation beneath has been filled. But in following the procedure well shall be above but not greatly above the water level. Such superposed sections are indicated in Fig. IV', and it will be perceived I 1 ends, or otherwise shaped. Figs. III and V that the' uppermost rise above the water line. These successively built up sections of the dredgingwells may be braced individuall as they are built to place, and in Fig. IV I h ve indicated braces 9, securing them to the growing shaft 2.

Given such a caisson so dimensionally related to the shaft of the pier to be built, and so equipped with dredging wells, the operation is in its general character the usual one. Because the caisson may be more precisely controlled and its position predetermined with substantial accuracy, thework of the building of the shaft may begin before the caisson comes to its ultimate depth, and may progress as the descent of the caisson continues, and may from beginning to end be carried on above water level, and so the necessity of resorting to cofier-dam structure in order to build the shaft, may be overcome, and the coifer-dam dispensed with. The sectional shells which form the walls of the dredging wells may be built one upon another gradually as the sinking of the caisson progresses. When the caisson has come to its ultimate position (and with a precision of place not hitherto attainable), the excavated spacebenath may be filled in usual manner,

to the bases of the dredging wells. The sectional shells which constitute the walls of the wells may then beitaken away,and may be used again, although in particular situations it may be found advantageous to abandon them or part of them,'as false work not worth salvage. The building ofthe pier progresses from this point forward in usual manner.

Theinvention is applicable, whatever be the shape of the pier,elliptical, circular, octagonal, polygonal, dumb bell shaped, parallel sided, with square, rounded,;or' pointed of the drawings show a pier of elongate plan with opposite parallel sides, rounded at the up-stream end, and square at the down-stream end, butit will be understood that this particular shape is merely the shape found in the instance chosen for illustration, by way of example, and is accidental merely to the disclosure of the invention. 7

The invention is not limited in its applicability to the erection of bridge piers; Fig. VI illustrates its application in the erection of a retaining walL, The retaining wall 10 is shown in cross-section, and will be'understood to be of indefinite length. It may be built in sections. sunk in the manner already described, is

- equipped with a dredging well or dredging wells, of which one is shown at 13, and shown to be external of the space occupied by the neat work of the wall,.to which the numeral 10 is immediately applied. As in the case of the pier, the neat work 10 may be erected as the caisson sinks, or in particular instances it may be erected after the caisson has come The caisson'12 which is" th rest and the footing has been completed. The dredging wells are a temporary provision; they ordinarily will have no continuing existence in the finished job. Filling m:

terial may eventually rest against the wall, as

indicated by the dotted line 11, and the widening of the caisson and the provision of the dredging well or wells are conveniently arranged on that side of the wall against which the fill 11 eventuallyis to rest.

Fig. VII similarly shows a dam structure whose footing is shaped and sunk in accordance with my invention. The neat work of the dam is'indicated at 14, the caisson which is employed in the sinking and forming of the footing of the dam is indicated at 15, and the position of a dredging well external to the space eventually occupied by the neat work, is indicated at 16.

Fig. VII serves additionally to indicate that, while the invention is found in the provision of a dredging well or wells external to the space occupied by the neat work, it does not forbid the provision of and the use of another dredging well or other dredging wells arranged according to the hitherto existing practice, within the neat-work space. In Fig. VII'a dredging Well so situated is. indicated at 17, and it will be understood that generally in the practice of my invention, a dredging sive of a plurality of walls with filled or unfilled'space between, and masonry structures generally, including of course such as are built wholly or partially of concrete. The ground where erection is made may be water soaked or dry, submerged or above water level.

The caissons employed may be formed of wood, steel, concrete, or reenforced concrete,

or of a combination of these materials. In

manner of sinking the caisson may be an open caisson (using a phrase current in the industry), or in contra-distinction, it may be a pneumatic caisson, or it may be a caisson in which the open and pneumatic systems are successively employed. The dredging wells Y may be of-any suitable shape and size, and may be formed of any suitable material, of wood, metal, concrete, reenforced concrete, or of other material. I Though advantageously erected progressively and section upon sec- 1 tion, they need not be sectional, and if sectional they may be made of sections of any convenient length.

In consequence of the use my invention, 7 I have more complete control in sinking or lowering cribs or caissons, and consequently accomplish a more exact placement of the footing of the ultimate structure. Tenden-' of sinking, I may gain added weight, and effeet the sinking of the caisson with greater speed. The avoidance of the necessity of using cofier-dams, a matter already mentioned,

is manifestly advantageous. I can sink a caisson to a given depth using the open dredg- "ing method to a maximum extent and with a minimum resort to the pneumatic method,

and can safely sink a caisson to a greater depth than is possible under the practice hitherto available.

In the ensuing claim the term masonry is used in larger sense, inclusive of concrete and such like materials applied in bulk and shaped to place. I

I claim as my invention: 4

The method herein described of building a masonry structure which consists in excavating material from beneath a caisson and removing the excavated material externally of the lines of the neat work ofthe structure.

In testimony whereof I have hereunto set my hand.

JAMES SMITH MILLER. Y 

